1. Field of the Invention
The present invention relates to certain entities for a communication system and in particular to release of resources after termination of a data flow in a communication system.
2. Description of the Related Art
A communication system is a facility which facilitates communication between two or more entities such as communication devices, network entities and other nodes. A communication system may be provided by one more interconnect networks. One or more gateway nodes may be provided for interconnecting various networks of the system. For example, a gateway node is typically provided between an access network and other communication networks, for example a core network and/or a data network. The communication may comprise, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on.
A user may communicate via a communication system and access various applications by means of an appropriate communication device. An appropriate access system allows the communication device to access to the communication system. An access to the communications system may be provided by means of a fixed line or wireless communication interface, or a combination of these. Examples of wireless access systems include cellular access networks, various wireless local area networks (WLANs), wireless personal area networks (WPANs), satellite based communication systems and various combinations of these.
A communication system typically operates in accordance with a standard and/or a set of specifications and protocols which set out what the various elements of the system are permitted to do and how that should be achieved. For example, it is typically defined if the user, or more precisely user device, is provided with a circuit switched bearer or a packet switched bearer, or both. Also, the manner in which communication should be implemented between the user device and the various elements of the communication and their functions and responsibilities are typically defined by a predefined communication protocol. Various functions and features are typically arranged in a hierarchical or layered structure, so called protocol stack, wherein the higher level layers can influence the operation of the lower level functions.
In cellular systems a network entity in the form of a base station provides a node for communication with mobile devices in one or more cells or sectors. It is noted that in certain systems a base station is called ‘Node B’. Typically the operation of a base station apparatus and other apparatus of an access system required for the communication is controlled by a particular control entity. The control entity is typically interconnected with other control entities of the particular communication network.
A non-limiting example of another type of access architecture is a concept known as long term evolution (LTE). A particular example of such systems is the Evolved Universal Terrestrial Radio Access (E-UTRA). An Evolved Universal Terrestrial Radio Access Network (E-UTRAN) consists of E-UTRAN Node Bs (eNBs) which are configured to provide base station and control functionalities. In these systems various functions that have been conventionally handled based on centralised control can be handled in a distributed manner. This kind of distributed architecture is sometimes referred to as a “flat architecture”. For example, the eNBs nodes can provide independently E-UTRA features such as user plane radio link control/medium access control/physical layer protocol (RLC/MAC/PHY) and control plane radio resource control (RRC) protocol terminations towards the user devices.
In the distributed systems, for example those based on the long term evolution concept, communications can be handled based on layer 2 (L2) architecture. A medium access control (MAC) can be employed for providing logical channels for carrying the data traffic flows. Each logical channel is configured with a radio link service profile (RLSP). The profile defines the quality of service (QoS) treatment to be given to data that is queuing in a given logical channel. Only a limited number of logical channels may be available, and thus any unnecessary “open” logical channels should be avoided. It is down to the layer 2 (L2) functional entities determine the termination of the data flows, and to clear the assigned radio link service profiles to enable reuse of the freed logical channels for future traffic flows.
The current L2 architecture presents some challenges due to the distributed nature of functionalities that relate to the logical channels. A logical channel is typically provided by at lest one medium access control (MAC) entity. Any data content therein waiting for transfer is emptied by a packet scheduler. The quality of service (QoS) of a logical channel is configured by a radio resource control (RRC) entity. This can be provided by setting appropriate radio link service profile parameters. Data may be queued into one or more logical channels based on the quality of service requirements of that data flow. For example, in a long term evolution arrangement this function is performed by means of a packet data convergence protocol (PDCP). Hence the determination of the end of traffic flow needs to be a coordinated activity that requires inter-functional messaging. A problem in here is that that the current layer 2 entities do not provide appropriate inter-functional messaging features.
The problem may not exist in the current cellular systems since in these the release and connection closure is initiated typically on a higher level layer wherefrom the closure then propagates to lower level layers and eventually provides functions such as closure of a packet data protocol (PDP) context. This type of release, however, may not always be appropriate in packet data networks and/or distributed systems. For instance, a packet data network may not employ a higher level layer to provide the explicit signaling that might be required for termination of a connection.
Thus there is a problem in relation to clearing resources from various functional entities once data traffic has ended on a logical channel. Also, it might be advantageous in certain situations if the state of the associated functional entities is consistent with respect to the status of the respective logical channel or channels.